More and more MS CRM developers are experiencing this error message:
A schema validation error has been detected at line 21087, position 16.
This error shows up if you want to import a customizations file which has been exported from a system which has the Update Rollup package 1 installed.
There may be multiple reasons for this error to show up, but at least one of them is the existence of one of these lines in your code:
To solve the error message, just remove the line from the code or install the rollup package 1. For information and download of the package go here: http://support.microsoft.com/default.aspx/kb/922815